It was Easter last year. Mum and I were at a Vietnamese restaurant in Sydney. At 27, I was vaguely aware that there was no longer infinite time left for me to have children. I loved my job as a reporter. I didn't want kids any time soon. But I didn't want all my options to vanish while I was busy filing stories. So sitting there, facing her, I asked the question.

"Mum, you know how you had me late," I said cautiously. "Did you have any problems conceiving me?" Her eyes flickered. She is Malaysian Chinese, with short salt-and-pepper hair. She moved in her seat. "Maybe this isn't the right time to tell you." Shrug. "But your father is not your father. We had problems conceiving and it turned out your father couldn't. So we used a donor."

WHAT?

"You're joking! Mum - are you joking?"

"No, no."

Half a beat.

"It doesn't make a difference, does it, Sarah?" She wasn't actually asking me. She wanted reassurance.

I wanted to scream, to rip the tablecloth off, to go to the bathroom and cry. But my mother doesn't cope well with that kind of thing.

"No," I said. "It doesn't."

That was my first lesson in being donor-conceived: your feelings about the whole business come last.

Growing up in Sydney, I was very close to my father, a travel agent whose family - from white, middle-class Adelaide - we visited every Christmas. When I was too little for school, he'd wake up early and leave me drawing exercises to do. He took me to sport and to work with him on weekends. When I started high school he was pretty strict: he'd left school without finishing and wanted the very best education for me.

When I was 15 and studying German, I decided to go on a three-month student exchange to Germany. At the airport, I suddenly felt a lurch at the thought of leaving my parents and all that familiarity.

On a white Christmas Day in Germany, I received a phone call. My grandfather was in his 90s and still living at home. Something had gone wrong with the electricity in his house and my father had gone up on the roof to take a look. He was electrocuted and fell.

When I flew home a day or so later, he was in a coma. He never woke up. The machine monitoring his vital signs flatlined that evening. I have no siblings. My only immediate family is my mother. Or so I thought.

What I now know is that my parents began going to the Human Reproduction Unit at the Royal North Shore Hospital (RNSH), a Sydney public hospital, in 1982. It was just before the AIDS scare fully broke.

I started digging. I contacted the clinic for my medical records. The RNSH Human Reproduction Unit had been taken over by IVF Australia, part of the Australian Stock Exchange-listed Virtus Health, which is worth hundreds of millions of dollars. IVF Australia keeps all records created by the public hospital.

I rang IVF Australia and was put onto a woman who handles these cases - people like me, the babies who come back to ask questions. I'll call her Mary. Mary took my details, but said she probably wouldn't be able to tell me my donor's name because when I was conceived in 1982, the law was different. What I've found out since is that there was no law.

Australia's assisted reproductive technology industry is today worth more than a billion dollars. It makes money out of human life. But crazily, there is no national legislation regulating the industry. Some states have acts governing the industry, but not all. My home state of NSW is one of the most enlightened for donor-conceived people, but even here, only children born after January 1, 2010 - that is, only toddlers - have the right to identifying information about their donors. The rest, like me, don't have that right.

Because the industry is unregulated nationally, no one knows exactly how many donor-conceived people exist, but the Donor Conception Support Group estimates that within Australia there are about 60,000.

At the NSW public hospital clinic where I was conceived, men donated sperm anonymously. Each man was assigned a donor code. Mary said she'd be able to find my donor code, but it would only yield very basic family medical history. There would be no name, no information on what he looked like, or whether he shares my weakness for olives. It was very disappointing. Still, I wanted anything they had.

Mary said she'd call in a fortnight. I was on edge while I waited. Everything I knew about myself had been blown apart at that dinner with my mother. Since then, I barely recognised my own face in the mirror. Mary offered a small glimmer of hope. From the information she could find, perhaps I would slowly be able to reconstruct who I was.

Eventually she rang back and said that she had found the file, but the information about my donor had been cut out and destroyed by the clinic. What had been destroyed was not my donor's name, but the three-letter donor code. This code tells you how many times, and when, the donor's material had been used, and what the donor's medical history was. It was the key to the pitifully small amount of family information that these clinics hand out to people like me.

Without any donor code, I am apparently a miracle birth. I am adrift. I will never find my biological father or my half-siblings. Mary said she couldn't give me access to the mutilated records because they didn't belong to me. They belonged to my mother.

I asked my mother for her permission to access the files - but she refused out of shame. When I was conceived in the 1980s, parents didn't choose a sperm donor. Donors were matched to the would-be father (based on factors such as height and eye colour) to minimise the chance of "embarrassing" revelations. Clinics told parents it was best to never tell anyone the truth about their child's genetic origins.

My mother had only told a handful of people the truth about me. Most of them have been dead for years. I kept asking Mum for permission to access the records but it took about six months before she finally agreed. In a meeting with IVF Australia, I was given a photocopy of what was apparently the whole file. Only two pages related to the treatment that resulted in my conception, and the column for the donor code was gone.

IVF Australia's medical Director, Associate Professor Peter Illingworth, explained that for a period in the early 1980s, all conception record codes at that clinic had been destroyed. The head of the clinic at that time was Professor Douglas Saunders. Illingworth said there might have been concerns over moves to open records so staff destroyed the codes to protect donor anonymity. With no code information available, the door was open for the clinic to use a donor's sperm multiple times. One of the very few early guidelines for the industry revolved around limiting the number of times a donor's sperm could be used to 10.

In a 2005 interview with the ABC's Four Corners, Saunders admitted his clinic had breached this limit. I asked Illingworth whether my donor would have been checked for HIV/AIDS. He said not necessarily, and added that there were two cases in other Sydney clinics at that time where women died from AIDS contracted through donor insemination. "That was what made clinics stop deleting donor records," he said.

I asked him how he could know whether I, conceived in 1982, had the virus. "Be assured that you would have known it by now," he said.

Three months after my conversation with Illingworth, he contacted me and said he had spoken to Saunders and wanted to clarify some things. He told me that all sperm used in late 1982 was frozen, and quarantined for six months to prevent the spread of AIDS. And no more than 10 siblings were created from any one donor.

I kept digging. I tracked down the nurse who had destroyed the record of my code. Back then, she had been a good friend of my mother's, who also worked at RNSH. The nurse had treated my mother at the Human Reproduction Unit.

I called her early on New Year's Eve and she was astonishingly direct. "I've often thought I was going to get these kinds of calls," she said. "There were a couple of girls I was friendly with at the time."

We talked about her daughter, who is the same age as me; we played together at the same crèche. The nurse said we should all go out to dinner sometime. I couldn't believe how surreal this was. Did she have any idea how huge this call was for me? Then she said she remembered my donor code. It was AFH. I wrote it down and stared at the letters. The nurse was rattling on. She told me my donor was a young science student, in his 20s, with similar colouring to my dad. Then she reeled off some stats about my dad - height, eye colour, hair colour - that were still buried in her mind. They were correct.

"When your mother had her treatment, the donors were chosen by me," she said. "We did it on the basis of the physical characteristics of the father. All the donors were medical or university students. As soon as a baby was born and healthy, the donor code was destroyed. We cut it out so that it couldn't be traced. Deep down, I knew it wasn't going to be the right thing. You shouldn't lose that information. But the donors were told they wouldn't be contacted."

The room was spinning, but I kept taking notes. "Professor Saunders would have given the order for the codes to be destroyed," she said. "But it was what everyone in Australia was doing at that time."

I asked her about siblings. About my siblings. I had never spoken the words aloud before. "I think probably we had a limit of 10," she said. "We kept going until we reached 10 and then that donor was withdrawn."

She said she couldn't remember the name that matched donor code AFH. "I could call Doug Saunders and ask him," she said. "I have a good relationship with him. He'll give me an honest answer. We've come a long way with a lot of things. It was a very naive world; [you'd] stick your fingers in your ears and hope the problem goes away."

After several months of waiting, I rang her. She didn't answer. Later, she left a confused voicemail saying she must have been mistaken and I should trust that the clinic was doing the best it could for me.

Perhaps the most disturbing news of all was that according to my file, my mother was treated on eight separate days during the cycle in which I was conceived. But the clinic told me they had no corresponding records of any donor sperm being used on those eight days. And yet I exist.

How many other children were made on those eight days of whom there is no record? How many other unrecorded children have been made at other times at that clinic? How many children have been made at private clinics with even less oversight? How many half-siblings are there who to this day don't know each other?

Today, I have an unofficial donor code. I have no right to access any files that could match that code with a name. In NSW, there's a voluntary register for children and donors who want to be found. But I can't join it. When I tried, I was told they couldn't add me without my code being verified by my clinic. And my clinic refuses to acknowledge what that nurse told me.

Let me be clear: I don't need another parent. I couldn't have asked for a better father than the man who brought me up. But I could do with some answers about why I am the way I am, who my family is, and what genetic time bombs I should watch out for. I would like to know who my biological father is, and to have an amicable relationship with him. You'd think that the former, at least, would be a legal right.

The reality is that I'll live my entire life as an only child who probably has more brothers and sisters than most people I know. In the end, because Saunders' clinic chose to destroy donor codes, I'll never find my family. I've come to terms with this, but I'd be lying if I said it didn't hurt. What happened to me in the 1980s could be happening right now. There is no national law keeping this industry's practices in check or protecting the rights of the child.

Without the right to the truth about our genetic origins, donor-conceived people will remain products of industry, not human beings.